Rubber plug for waterproof connector

Abstract: A double collar portion formed on a rubber plug intermediate opposite ends thereof and an umbrella-shaped end plug formed at a rear end of the rubber plug improve waterproofing in an electrical terminal. The collar portion is held in intimate contact with an inner peripheral surface of a tubular terminal-receiving chamber to form a seal therebetween. An open end of the tubular terminal-receiving chamber is closed by the end plug without a gap or recess, thereby eliminating the possibility of collection of water and virtually eliminating the possibility of water leaking into the terminal.

Description: BACKGROUND OF THE INVENTION This invention relates to a rubber plug for a waterproof connector and more particularly to a rubber plug wherein the plug forms a seal between a housing and a wire within the waterproof connector. One known rubber plug for a waterproof connector is shown in Figs. 4 and 5. A rubber plug 2 of a cylindrical shape having a through hole 2a extending along a centerline thereof for passing a wire 1 therethrough has two flange-like collars 2b formed at a rear end portion 7 thereof. A front end portion 5 of the rubber plug has an outer diameter such that the front end portion 5 can be compressively clamped by an insulation barrel 3a of a terminal 3 with the wire 1 passing through the front end portion 5. On the other hand, a connector housing 4 (Fig. 5) has a tubular terminal-receiving chamber 4a for retaining and holding the terminal at its front portion 8, the terminal receiving chamber having an open rear end portion 9. The open rear end portion 9 has a diameter such that the collars 2b are held in tight contact with the peripheral wall when the rubber plug 2 and the wire 1 are inserted into the housing 4. The wire 1 is passed through the through hole 2a of the rubber plug 2, and a covering or insulating material is peeled from the front end portion 5 of the wire. The front end portion 5 of the rubber plug 2 is fixedly secured to the insulation barrel 3a of the terminal 3 by compressive clamping, and a conductor or exposed portion of the wire 1 is connected to a wire barrel 6 of the terminal 3 by compressive clamping. When the terminal 3 is inserted into the terminal receiving chamber 4a of the connector housing 4, the terminal 3 defining the leading side is retained at the inner end portion of the terminal receiving chamber 4a, and the rubber plug 2 at the rear end 9 of the terminal is received in the terminal receiving chamber 4a in intimate contact with the peripheral wall of the chamber, with the collars 2b being slightly elastically deformed. When water is poured on the open end 9 of the terminal receiving chamber 4a, the intrusion of the water is prevented because of the intimate contact between the peripheral wall of the terminal receiving chamber 4a and the collars 2b of the rubber plug 2, thereby achieving a waterproof effect. In the above conventional rubber plug for a waterproof connector, however, if the rear end face 7 of the rubber plug 2 is not flush with the open end of the terminal receiving chamber 4a, a water collecting recess R may be formed. In such a case, when the wire vibrates, although water will not intrude immediately, a gap is formed between the collars 2b and the peripheral wall of the terminal receiving chamber 4a. This vibration allows the collected water to intrude into the terminal receiving chamber 4a. FR-A-2 415 375 shows a watertight electric coupling device comprising a plug with an end plug, said end plug having an umbrella shape to cover the open end. SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber plug for a waterproof connector that overcomes the above-described problems in the conventional plug and more surely prevents water from collecting and seeping into the terminal. Solution of this object is achieved by what is claimed in claim 1. Accordingly, the present invention provides a waterproof connector having a rubber plug, said rubber plug comprising a wire passed therethrough, said rubber plug together with said wire being insertable into a tubular passage of the waterproof connector to form a seal between a wall of said tubular passage and said wire, said rubber plug having: a main plug portion that forms said seal between said wire and said tubular passage by means of a pair of flange-like collars being held in intimate contact with the inner peripheral surface of said tubular passage, and an end plug connected to said main plug portion at a side of the connector where an open end of said tubular passage is disposed, said end plug closing said open end, wherein said end plug having a lip portion, said lip portion being tapered such that its diameter progressively increases away from said flange-like collars. In the invention of the above construction, when the rubber plug is inserted into the tubular portion of the waterproof connector, the end plug formed at that side where the open end of the tubular portion is disposed closes the open end thereby eliminating the possibility of collection of water at the open end portion. Due to the fact that the end plug has a lip portion which is tapered such that its diameter progressively increases away from said flange-like collars, collection of water in the vicinity of the open end portion is even more effectfully prevented. As described above, in the present invention, the open end of the tubular portion is waterproofed by closing the end plug thus preventing water from collecting and seeping into the terminal. Accordingly, even vibrations that may cause gaps to form between the peripheral wall of the tubular portion and the rubber plug will not cause water leakage. Furthermore, the end plug covers the entire open end portion. With this feature, the plug can be attached with a smaller force as compared with the type of construction in which a plug is pushed in for closing purposes. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described with reference to the following drawings, wherein: Fig. 1 is a cross-sectional view showing a preferred embodiment of the present invention; Fig. 2 is a perspective view of a conventional rubber plug for a waterproof connector; and Fig. 3 is a cross-sectional view showing the conventional rubber plug in a waterproof connector. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Fig. 1 is a cross-sectional view of one preferred embodiment of a rubber plug of the present invention for a waterproof connector showing the plug attached to a waterproof connector housing. In the drawings, a rubber plug 10 includes a cylindrical body 12 having a through hole 11 extending along a centerline thereof for passing a wire 20 therethrough. Two flange-like hollow collars 13 are formed on and project outwardly from the body 12. The collars 13 are disposed at a generally central portion of the body 12 in the axial direction. An end plug 14 is formed at a rear end of the rubber plug. An outer periphery of a front end portion of the rubber plug 10 is defined by a smooth cylindrical surface. The front end portion has a diameter such as to be compressively clamped by an insulation barrel 31 of a terminal 30. A female terminal portion 32 is formed at a front end portion of the terminal 30, and a wire barrel 33 is formed between the terminal portion 32 and the insulation barrel 31. A waterproof connector housing 40 has a terminal receiving chamber 41 in the form of a hollow tube. An opening 42 for passing a mating terminal therethrough is formed in a front end (shown at a lower side) of the terminal receiving chamber 41, and an opening 43 for passing the terminal 30 therethrough is formed at a rear end of the terminal receiving chamber 41. The rear open end portion 43 of the terminal receiving chamber 41 is formed into a cylindrical shape and the diameter of the end plug 14 is greater than the diameter of the rear open end portion 43 so as to cover the entire open end 43. Here, the rubber end plug 14 for closing the rear open end portion 43 is tapered in such a manner as shown in Fig. 1, so that the diameter progressively increases, i.e. the end plug has a lip portion and this lip portion being tapered such that its diameter progressively increases away from the collars 13. A lock piece 15 for retaining the terminal 30 is provided within the terminal receiving chamber 41 at its front portion. The operation of the embodiment of the above construction will now be described. First, the wire 20 is passed through the through hole 11 of the rubber plug 10 from that side of the rubber plug where the end plug 14 having the lip portion with progressively increasing diameter is formed, and a wire insulator or covering material is peeled from that portion of the wire projected from the other side of the rubber plug 10, thereby exposing the conductor. The cylindrical front end portion of the rubber plug 10 is put on the insulation barrel 31 of the terminal 30, and the insulation barrel 31 is compressively deformed, thus clamping the exposed ends of the wire 20 in the wire barrel 33. After the wire 20 and the terminal 30 are connected, the terminal 30 is inserted into the terminal receiving chamber 41 of the waterproof connector housing 40. During the insertion of the rubber plug 10, the cylindrical body 12 freely passes through opening 43, whereas the two collars 13 are kept in intimate contact with the inner peripheral surface of the terminal receiving chamber 41. Immediately before the terminal 30 is inserted into a predetermined position, the end plug 14 of the rubber plug 10 is brought into abutting engagement with the opening portion 43 of the terminal receiving chamber 41. Then, the rubber plug is further pushed until the terminal 30 becomes retained, so that the peripheral edge of the opening 43 is pressed into intimate contact with the inner surface of the lip portion of the end plug 14. In this condition, even if water is poured or those portions in the vicinity of the end of the terminal receiving chamber 41, water will not collect at the opening 43 since the opening is entirely covered with the lip portion of plug 14. Therefore, water will not intrude into the terminal receiving chamber 41. Covering of the opening portion 43 is enhanced by the lip portion being tapered such that its diameter progressively increases away from the collars 13 or the rim of the opening portion 43, respectively. As described above, the collars 13 are held in intimate contact with the inner peripheral surface of the tubular terminal receiving chamber 41. In addition, the open end of tubular portion is closed by the end plug, with no gap or recess formed, thereby eliminating the possibility of collection of water. While the invention has been described in detail with reference to preferred embodiments thereof, which are intended to be illustrative but not limiting, various changes may be made without departing from the invention, which is defined in the following claims.

Claims: A waterproof connector having a rubber plug, said rubber plug (10) comprising a wire (20) passed therethrough, said rubber plug (10) together with said wire (20) being insertable into a tubular passage (41) of the waterproof connector to form a seal between a wall of said tubular passage (41) and said wire (20), said rubber plug (10) having: a main plug portion (12) that forms said seal between said wire (20) and said tubular passage (41) by means of a pair of flange-like collars (13) being held in intimate contact with the inner peripheral surface of said tubular passage (41), and an end plug (14) portion connected to said main plug portion (12) at a side of the connector where an open end (43) of said tubular passage (41) is disposed, said end plug (14) closing said open end (43), wherein said end plug (14) has a lip portion, said lip portion being tapered such that its diameter progressively increases away from said flange-like collars (13). The waterproof connector of claim 1, wherein said tapered end plug (14) has a first portion having a diameter greater than a diameter of said pair of flange-like collars (13) and a diameter of the tubular passage (41), a second portion having a diameter equal to both the diameter of the tubular passage (41) and the diameter of the pair of flange-like collars (13) in the tubular passage (41), and a third portion having a diameter less than the diameter of the tubular passage (41) and the diameter of the pair of flange-like collars (13). The waterproof connector of claim 1 or 2, wherein said main plug (12) and said end plug (14) are a unitary structure. The waterproof connector of anyone of claims 1 to 3, wherein said tapered end plug (14) is pressed into intimate contact against said open end (43) of said tubular passage (41) to maintain a tight seal. A rubber plug for a waterproof connector, comprising a main plug portion (12) that forms a seal between a wire (20) and a tubular passage (41) inside the waterproof connector by means of a pair of flange-like collars (13) being held in intimate contact with the inner peripheral surface of said tubular passage (41), and an end plug (14) portion connected to said main plug portion (12) at a side of the connector where an open end (43) of said tubular passage (41) is disposed, said end plug (14) closing said open end (43), wherein said end plug (14) has a lip portion, said lip portion being tapered such that its diameter progressively increases away from said flange-like collars (13). The rubber plug of claim 5, wherein said tapered end plug (14) has a first portion having a diameter greater than a diameter of said pair of flange-like collars (13) and a diameter of the tubular passage (41), a second portion having a diameter equal to both the diameter of the tubular passage (41) and the diameter of the pair of flange-like collars (13) in the tubular passage (41), and a third portion having a diameter less than the diameter of the tubular passage (41) and the diameter of the pair of flange-like collars (13). The rubber plug claim 5 or 6, wherein said main plug (12) and said end plug (14) are a unitary structure. The rubber plug of anyone of claims 5 to 7, wherein said tapered end plug (14) is pressed into intimate contact against said open end (43) of said tubular passage (41) to maintain a tight seal.

Inventors: SAIJO EIJI, WAKATA SHIGEKAZU, SAIJO, EIJI, WAKATA, SHIGEKAZU, SAIJO, EIJI, C/O SUMITOMO WIRING SYST., LTD., WAKATA, SHIGEKAZU, C/O SUMITOMO WIRING SYST., LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1994
Main classification: H01R13
IPC codes: H01R13